Field Report: Airtools Voice Processor 2X

July 1, 2009

When I first heard Symetrix was shipping the new Airtools Voice Processor 2X microphone processor I couldn't wait to get a look at it. I'm a big fan of the 528E and I wanted to see how this new digital box would compare. The Voice Processor 2X features two independent channels of very low latency (less than 7ms) digital signal processing plus the ability to store up to 50 nameable presets. The processor can be tailored to each announcer's particular needs and it is easy to switch to their own personalized preset from the front panel. It contains two complete and independent channels of mic processing in 1RU. The 2X has two XLR analog inputs, either mic or line level, two XLR AES inputs, an RJ-45 Ethernet connection, a BNC connector for word clock and an RJ-45 jack for a remote control. The output section of the 2X consists of two XLR analog outputs at line level, or internally switchable to mic level, and two XLR AES outputs.

Airtools Voice Processor 2X

The 2X is set up by software on a host computer connected with standard CAT-5 cable directly, via an Ethernet switch or through an existing network. If you are not connecting through a network, the IP configuration on both the 2X and the host computer must be set manually, or you could use the default private IP address.

The 2X acquired its IP address from the DHCP server on the network. I started the software, ran the Connection Wizard and waited for the Wizard to discover the 2X (Figure 1). This took about 30 seconds. A very handy feature of the Connection Wizard is a button that will flash the LED meters on the connected 2X for easy identification in a multiple processor installation. Once you have determined which unit you want to connect to, just click the offline/online button and you are ready to set up the processor.


Performance at a glance

Two programmable mic channels
Extensive I/O
Compression, EQ, de-essing, downward expander, high- and low-pass filtering
Saves up to 50 presets
Ethernet accessible
Windows setup software

I found the setup menus to be very intuitive and easy to navigate. From the main screen you can chose which processing module to enable, disable, edit, whether to bypass the DSP or mute the channel. The presets are managed, recalled and stored from this menu as well. As you navigate through the screens you quickly realize how versatile and powerful this processor can be.

The processor consists of seven modules including compression, downward expansion, equalization, de-essing, highpass and lowpass filters, and voice symmetry. Choosig edit on the input tab opens the input control. On this screen are the mic or line level settings for each of the two analog inputs, or the digital trim adjustment if the AES inputs are used. Phantom power for condenser mics is chosen here, as well as phase inversion and muting. The two most impressive modules are the high- and low-pass filters, and the EQ. Use the HPF/LPF tab to edit the parameters of the high- and low-pass filters. Each filter features a 12, 24, or 48dB slope if needed, as well as variable frequency and resonance adjustment. The adjustments are represented on a graphical display that shows the frequency response curve for each channel. The high-pass filter works very well for eliminating rumble, wind or HVAC noise in difficult environments. The low-pass filter has the same features as the high-pass filter.

The EQ module is a four-band parametric equalizer that can be switched to either pre or post compressor. The frequency response curve of the EQ is also graphically presented, which makes setting up the EQ much simpler and quicker. The Comp tab opens the compressor screen. On this screen are the standard compressor settings threshold, ratio, attack, release, plus the added control of output gain or makeup gain for the compressor module. Compression and output metering is provided on this screen as well. The DS/EXP tab opens the de-esser and expander screen. The de-esser has a different approach on the 2X. Instead of the usual frequency and threshold adjustments the choices are now disabled, gentle, normal, or aggressive with no variables in between. The expander offers more control with the choices of threshold, ratio, attack, and release. Included on the screen is the metering for the de-esser and the expander.

On the output screen the output levels for both analog and digital are set. The analog range of +4 or -10 is set and voice symmetry can be set to active or inactive. Under the system tab are settings for the AES inputs and outputs. On this screen are settings for sync source, sample rate and word-clock termination. The AES output source for each of the two AES outputs can be chosen from a set of routing matrixes adding to the versatility of this processor. Each channel has an independent test tone generator which, when enabled, applies white noise, pink noise or sine wave to the input, which can be a handy tool for setting levels through the processor and console.

Figure 1

Figure 1

Real-world analysis

I connected three different mics to the processor: an Electro-Voice RE20, a Shure SM-7 and a Neumann U-87. The AES output was connected to a Klotz digital console and was monitored with Sony 7506 Headphones. Different voices were used, female and male on each of the three mics. I adjusted the processor until both the talent and I were pleased with the sound. The biggest difference I found between the 2X and the 528E is the precise tweaking that can be accomplished with the four-band parametric EQ, and the high- and the low-pass filters. The level of control afforded the engineer on the expander and compressor modules really makes the voice characteristics of the different announcers stand out.

The talent did not notice any latency issues and the transparency of the compressor was noticed at once. The de-esser never quite sounded right to me especially on the U-87. The choices always seemed a little too much or not enough. So it was disabled. After getting everything set just right the parameters were saved to a preset and the preset was named according to day part. Being able to choose a specific setup for each voice on the air was a big hit and the announcers easily learned to operate the front panel. A remote for this function would be nice. The remote control was not available at the time of this writing.

Security on the 2X can be set on two levels. The front-panel controls can be disabled, and the 2X can be password protected to prevent unauthorized access from the network side. There are no knobs and none of the parameters can be accessed from the front panel of the 2X, all changes must be made through the 2X software. This can be a hassle when changes need to be made quickly, but you don't need those little cages over the controls anymore.

Rice is the engineering director at Bonneville International St. Louis Radio Group.


Editor's note: Field Reports are an exclusive Radio magazine feature for radio broadcasters. Each report is prepared by well-qualified staff at a radio station, production facility or consulting company.

These reports are performed by the industry, for the industry. Manufacturer support is limited to providing loan equipment and to aiding the author if requested.

It is the responsibility of Radio magazine to publish the results of any device tested, positive or negative. No report should be considered an endorsement or disapproval by Radio magazine.

Receive regular news and technology updates. Sign up for our free newsletter here.